Reland: Add support for entering/exiting HTML fullscreen from OOPIFs.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index ee5ba2f46d048adfb7a41e085362982902908f19..dd59a10f8f7b2254f97b02da59e65e6f04d69c78 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1873,11 +1873,9 @@ void WebContentsImpl::ExitFullscreenMode(bool will_cause_resize) {
                         will_cause_resize));
 }
 
+// TODO(alexmos): Remove the unused |render_widget_host| parameter.
 bool WebContentsImpl::IsFullscreenForCurrentTab(
     RenderWidgetHostImpl* render_widget_host) const {
-  if (!RenderViewHostImpl::From(render_widget_host))
-    return false;
-
   return delegate_ ? delegate_->IsFullscreenForTabOrPending(this) : false;
 }